Emulsifiable insecticidal concentrates



EMULSIFIABLE INSECTICIDAL CONCENTRATES Harry S. Butler and Clarence C.Harvey, IL, Baton Rouge, La., assignors to Ethyl Corporation, New York,N. Y., a corporation of Delaware No Drawing. Application October 30,1952 Serial No. 317,818

Claims. (Cl. 1617-43) This invention relates to insecticidalformulations and more particularly to emulsifiable concentrates ofchlorinated insecticides.

In recent years, a number of powerful chlorinated insecticides have beendeveloped, such as lindane and chlordane. In use, these insecticides arenormally mixed with an inert carrier to facilitate application and usethereof. One preferred preparation of these insecticides is in the formof an emulsifiable concentrate which, prior to use thereof, can bediluted with water to produce a liquid adapted to be readily and easilysprayed, brushed, or otherwise employed to combat insects and pests.

The emulsifiable concentrates heretofore prepared have been excessivelycorrosive and have thus required special containers for storage andshipment, such as glass vessels or lined drums. These concentrates havegenerally been prepared with xylene or other non-polar solvent.Chlorinated insecticidal materials have limited solubility in suchsolvents at low temperatures and thus require blending with morepowerful solvents to prevent low temperature precipitation of theinsecticide, which, when precipitated, is relatively diificult toredissolve.

Various polar solvents have been found suitable as additives to theemulsifiable concentrates to improve the low temperature solubilityof'the insecticide. They include ketones, ethers, and esters. However,the addition of the latter compounds to emulsifiable concentratesconsiderably aggravates the problem of corrosion and necessitates theuse of corrosion-resistant containers for shipment and storage.

It is accordingly an object of this invention to provide an improvedemulsifiable insecticidal concentrate. A further object is to provide'aconcentrate of the above type having improved corrosion characteristics,while at the same time, having good low temperature solubilitycharacteristics. Another object of this invention is to provide anemulsifiable concentrate of the above type which can be stored andshipped in conventional thinwalled metal containers wherein thecorrosion rate should not materially exceed 0.001 in./year. Otherobjects and advantages of this invention will be apparent from thefollowing description.

It has now been found that emulsifiable concentrates of lchlorinatedinsecticides can be prepared which are highly stable at low temperaturesand which are essentially non-corrosive, such that they can be storedand packaged in metal containers if the insecticide is dissolved in asolvent blend consisting of a non-polar and polar solvent, thenon-polar:polar solvent ratio being controlled within relatively closelimits, and if, at the same time, the water concentration in theemulsifiable concentrate is maintained at a low level.

The weight ratio of non-po1ar:polar solvent should be maintained withinthe range of 8:1 and 1:2 and preferably the non-polar solvent should bebetween 55. and 65 percent by weight of the total solvent. The waterconcentrate, using the above solvent ratios, must be maintained below aou Per en by g t, based o t e ice total weight of the emulsifiableconcentrate, and preferably should be maintained below 0.10 weightpercent. in general, the lower the concentration of water below 0.2weight percent, the less corrosive is the concentrate for any givensolvent ratio. Accordingly, it is frequently desired to maintain thewater concentration below 0.05

1" tion.

weight percent of the total concentrate. Commercial grades of mostcommon insecticidal solvents contain substantially greaterconcentrations of water than is tolerable in insecticidal formulationsof the present inven- As noted above, however, the control of waterconcentration alone in formulations will not prevent corrosion, if thesolvent ratio is not maintained within the above critical range.

In general, the concentration of the insecticide can range from about 1percent to about 50 percent. Lower concentrations of insecticides arenot normally desired clue to the relatively high cost of solvent. Theupper concentration of the insecticide is merely controlled by thesolubility characteristics of the solvent system, and the temperatureconditions to which the formulation Wlll be subjected. Preferably, theinsecticidal concentration is between 10 percent and 30 percent byweight of the total emulsifiable concentrate.

The total weight of the solvent blend, i. e. polar and non-polarsolvents, should generally be between 6090 percent by weight of thetotal concentrate.

The non-polar solvents which are useful with the present invention arearomatic hydrocarbons such as benzene, xylene, toluene, mesitylene,kerosene, naphthalene, methylated naphthalenes, aromatic petroleumderivatives, and chlorinated solvents such as ethylene dichloride,mon-ochlorobenzene, carbon tetrachloride, and chloroform.

The polar solvents especially useful in the present invention areketones, ethers, esters, alcohols and aldehydes. Typical examples ofothers are acetal, ethyl ether, butyl ethyl ether, benzoyl butyl ether,dioxane, benzoyl methyl ether, propyl ortho tolyl ether andZ-naphthapropyl ether. Typical examples of esters suitable as a polarsolvent in the present invention are butyl acetate, ethyl acetate, andmethyl propionate. Typical examples of ketones are acetone,cyclohexanone, isophorone, methyl ethyl ketone and methyl isobutylketone. Suitable alcohols are methanol, ethanol, normal propanol andisopropanol. Aldehydes which are suitable for this invention arebutyraldehyde, benzaldehyde and ortho tolualdehyde.

The emulsifying agents useful with this invention can be selected from awide variety of compounds. In general, any non-ionic or anionicemulsifier is suitable. However, preferably a blend of non-ionic andanionic emulsifiers is employed since such a blend assures emulsionstability in both hard and soft water. The concentration of theemulsifier is generally between 2-10 percent by weight of theconcentrate, and is preferably about 5 percent thereof.

The emulsifiable concentrates of the present invention, as noted above,are mixed and emulsified with water prior to use. In general, thewaterzconcentrate weight ratio can be between about 20:1 and 100:1,although greater or lesser concentrations are desired in some instances.

The following examples demonstrate the benefits of emulsifiableconcentrates which have exceptionally good low temperature stability andlow corrosion characteristics. In these examples, all quantities aregiven in percent by weight.

Example I An emulsifiable insecticidal concentrate was preparedcontaining 20 percent lindane dissolved in 45 percent Solvesso 150 and30 percent isophorone. The concentrate also contained 5 percent Toximulas an emulsifier. Solvesso 150 is a commercial solvent mixture ofpolyalkyl benzenes containing approximately 52 percent tetramethylbenzene and 25 percent dialkyl benzenes, the remaining quantities of thesolvent consisting of trialkyl benzenes and naphthalene. Toximul is acommercially avail-able emulsifying agent consisting of a blend ofnonionic and anionic emulsifiers. The water concentration in thisconcentrate was 0.08 percent.

Corrosion tests were made with the above concentrate on iron and wasfound to have a corrosion rate of less than 0.00001 iii/year. The testswere conducted using sealed glass vials containing samples of theconcentrate and weighed test pieces of iron. The vials were stored at 50C. for about a three-weeks period, after which time the corrosion of theiron pieces was measured by weight loss.

The temperature of precipitation of this concentrate is below about F.

Example II Example I was repeated except that the water concentration inthe emulsifiable concentrate was merely reduced to 0.58 percent of thetotal solution. Similar corrosion tests were conducted and the corrosionrate was found to have increased to an untenably high value of 0.018in./year. It will thus be seen that although the water concentration inExample II was only about 7 times that of Example I, the corrosion rateincreased in excess of 1800 times, even though the actual waterconcentration was only a fraction of 1 percent in both examples.

Example III Example I was repeated except that the water concentrationwas reduced to 0.14 percent and Antarox B-201 (a commercial grade ofalkyl polyoxethylene glycol ester) was employed as the emulsifier.Corrosion tests conducted as in Example I showed the exceedingly lowcorrosion rate of 0.00003 in./year.

Example IV Example III was repeated except that the water concentrationwas only reduced to 0.47 percent. Corrosion tests with this concentrategave a corrosion rate of 0.015 in./year. In comparing Examples III andIV it will be seen that an increase of approximately 3-fold in the waterconcentration resulted in a 500-fold corrosion rate increase.

Example V An emulsifiable concentrate was prepared employing 20 percentlindane, 37.5 percent xylene, 37.5 percent isophorone and 5 percentAntarox B-201. The water concentration in this concentrate was reducedto 0.10 percent. Corrosion tests similar to those of Example I gave acorrosion rate with this concentrate of only 0.00003 in./year.

Example VI Example V was repeated except that only'19 percent xylene wasemployed with 56 percent isophorone. The water concentration was againreduced to a very low value (0.008 percent). Corrosion tests with thisconcentrate gave the excessively high corrosion rate of 0.034 in./year.It will be seen from this example that even though the waterconcentration is carefully controlled, it is also necessary to controlthe non-polarzpolar solvent ratio to attain a non-corrosive system.

Example VII An emulsifiable concentrate containing 20 percent lindane,45 percent mixed methylated naphthalenes, 30 percent cyclohexanone, and5 percent sulfonated. oil containing polyoxethylene sorbital esters(Atlas (1-2081) Was tested for corrosion similar to that of Example I.The water concentration of the composition was 0.12 percent. Thecorrosion rate with this composition was found to be 0.0004 in./year.

Examples VIII Example VII was repeated except that the waterconcentration was only reduced to 0.60 percent. In this example, thecorrosion rate was 0.012 in./year as compared with only 0.0004 ofExample VII.

Example IX An emulsifiable concentrate was prepared containing 20percent lindane, 56 percent methylated naphthalenes (Velsicol AR50), 19percent isopropyl alcohol, and 5 percent Antarox B201. The waterconcentration was reduced to 0.02 percent. This concentrate gave acorrosion rate of only 0.0001 in./year.

Example X Example IX was repeated except that the nonpolarzpolar solventratio was substantially reduced. The concentrate consisted of 20 percentlindane, 19 percent mixed methylated naphthalenes, 56 percent isopropylalcohol, and 5 percent Antarox B201. The water concentration was alsoreduced to 0.02 percent. However, with such a high concentration ofpolar solvent, the corrosion rate with this concentrate increased to0.053 in./year.

Example XI An emulsifiable concentrate comprising 20 percent lindane, 45percent ethylene dichloride, 30 percent butyl acetate, and 5 percentemulsifying agent, the concentrate having a water concentration of 0.1percent.

Example XII An emulsifiable concentrate comprising 10 percent lindane,50 percent benzene, 35 percent butyraldehyde, and 5 percent emulsifyingagent, the water concentration of the concentrate being 0.05 percent.

Example XIII An emulsifiable concentrate containing 20 percentchlordane, 45 percent Solvesso 150, 30 percent isophorone and 5 percentToximul, the water concentration in the concentrate being 0.08 percent.

Example XIV An emulsifiable concentrate consisting of 20 percentchlordane, 35.5 percent xylene, 35.5 percent isophorone, and 5 percentAntarox B-20l, the water concentration being 0.1 percent.

As is believed apparent from the foregoing, the present inventiondiscloses an emulsifiable insecticidal concentrate which is bothrelatively non-corrosive and highly stable against insecticideprecipitation at low temperatures. By maintenance of the waterconcentration in the insecticide at a level below about 0.2 percent ofthe formulation, and maintaining the non-polar:polar solvent ratioWithin definite limits, an insecticidal formulation can be prepared,stored and shipped in thin-walled metal receptacles or containers,without undue corrosion.

We claim:

1. An emulsifiable insecticidal concentrate, comprising a chlorinatedinsecticide, a non-polar solvent for said insecticide, and a polarsolvent for said insecticide, the weight ratio of non-polarzpolarsolvent being between 8:1 and 1:2, said concentrate having water presentin a concentration not exceeding 0.2 percent by weight of theconcentrate.

2. An emulsifiable insecticidal concentrate in accordance with claim 1wherein the non-polar solvent comprises 55-65 percent by weight of thetotal solvent.

3. An emulsifiable insecticidal concentrate, comprising a chlorinatedinsecticide, a non-polar solvent for said insecticide, and a polarsolvent for said insecticide, the

aveslih 5 weight ratio of non-polarzpolar solvent being between 8:1 and1:2, said concentrate having Water present in a concentration notexceeding 0.1 percent by weight of the concentrate.

4. An emulsifiable insecticidal concentrate, comprising between 1-50percent by Weight of a chlorinated insecticide, a non-polar solvent forsaid chlorinated insecticide, a polar solvent for said chlorinatedinsecticide, the weight ratio of the non-polarzpolar solvent beingbetween 8:] and 1:2, between 2-10 percent by Weight of an emulsifyingagent, and Water in a concentration below about 0.2 percent of saidconcentrate.

5. An emulsifiable insecticidal concentrate, comprising between 10-30percent by Weight of a chlorinated insecticide, between 60-90 percent byweight of a solvent 6 blend including a non-polar solvent for saidchlorinated insecticide, and a polar solvent for said chlorinatedinsecticide, the weight of said non-polar solvent being between 55-65percent of the total Weight of the solvent blend, about 5 percent or" anemulsifying agent, and Water in a concentration below about 0.1 percentby weight of said concentrate.

References Cited in the file of this patent UNITED STATES PATENTS2,140,519 Elston Dec. 20, 1938 2,165,486 Jewel July 11, 1939 2,497,101Starr Feb. 14, 1950 2,524,590 Boe Oct. 3, 1950

1. AN EMULSIFIABLE INSECTICIDAL CONCENTRATE, COMPRISING A CHLORINATEDINSECTICIDE, A NON-POLAR SOLVENT FOR SAID INSECTICIDE, AND A POLARSOLVENT FOR SAID INSECTICIDE, THE WEIGHT RATION OF NON-POLAR:POLARSOLVENT BEING BETWEEN 8:1 AND 1:2, SAID CONCENTRATE HAVING WATER PRESENTIN A CONCENTRATION NOT EXCEEDING 0.2 PERCENT BY WEIGHT OF THECONCENTRATE.